title: Reduced brain/serum glucose ratios predict cerebral metabolic distress and mortality after severe brain injury.
abstract: BACKGROUND
  The brain is dependent on glucose to meet its energy demands. We sought to evaluate the potential importance of impaired glucose transport by assessing the relationship between brain/serum glucose ratios, cerebral metabolic distress, and mortality after severe brain injury.
  
  
  METHODS
  We studied 46 consecutive comatose patients with subarachnoid or intracerebral hemorrhage, traumatic brain injury, or cardiac arrest who underwent cerebral microdialysis and intracranial pressure monitoring. Continuous insulin infusion was used to maintain target serum glucose levels of 80-120 mg/dL (4.4-6.7 mmol/L). General linear models of logistic function utilizing generalized estimating equations were used to relate predictors of cerebral metabolic distress (defined as a lactate/pyruvate ratio [LPR] ≥ 40) and mortality.
  
  
  RESULTS
  A total of 5,187 neuromonitoring hours over 300 days were analyzed. Mean serum glucose was 133 mg/dL (7.4 mmol/L). The median brain/serum glucose ratio, calculated hourly, was substantially lower (0.12) than the expected normal ratio of 0.40 (brain 2.0 and serum 5.0 mmol/L). In addition to low cerebral perfusion pressure (P = 0.05) and baseline Glasgow Coma Scale score (P < 0.0001), brain/serum glucose ratios below the median of 0.12 were independently associated with an increased risk of metabolic distress (adjusted OR = 1.4 [1.2-1.7], P < 0.001). Low brain/serum glucose ratios were also independently associated with in-hospital mortality (adjusted OR = 6.7 [1.2-38.9], P < 0.03) in addition to Glasgow Coma Scale scores (P = 0.029).
  
  
  CONCLUSIONS
  Reduced brain/serum glucose ratios, consistent with impaired glucose transport across the blood brain barrier, are associated with cerebral metabolic distress and increased mortality after severe brain injury.
authors.affiliation: Neurological Intensive Care Unit, Departments of Neurology and Neurosurgery, Columbia University College of Physicians and Surgeons, Milstein Hospital 8 Center, 177 Fort Washington Ave, New York, NY, 10032, USA.
authors.forename: Pedro
authors.initials: P
authors.lastname: Kurtz
authors.forename: Jan
authors.initials: J
authors.lastname: Claassen
authors.forename: J Michael
authors.initials: JM
authors.lastname: Schmidt
authors.forename: Raimund
authors.initials: R
authors.lastname: Helbok
authors.forename: Khalid A
authors.initials: KA
authors.lastname: Hanafy
authors.forename: Mary
authors.initials: M
authors.lastname: Presciutti
authors.forename: Hector
authors.initials: H
authors.lastname: Lantigua
authors.forename: E Sander
authors.initials: ES
authors.lastname: Connolly
authors.forename: Kiwon
authors.initials: K
authors.lastname: Lee
authors.forename: Neeraj
authors.initials: N
authors.lastname: Badjatia
authors.forename: Stephan A
authors.initials: SA
authors.lastname: Mayer
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000032:analysis / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D001930:Brain Injuries / Q000209:etiology / Q000378:metabolism* / Q000401:mortality / Q000503:physiopathology; D002560:Cerebrovascular Circulation / Q000502:physiology; D003128:Coma / Q000209:etiology; D005260:Female; D015600:Glasgow Coma Scale; D005947:Glucose / Q000032:analysis* / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000008:administration & dosage; D008297:Male; D017551:Microdialysis; D008875:Middle Aged; D011446:Prospective Studies; D012189:Retrospective Studies; D012720:Severity of Illness Index
chemical_list: D001786:Blood Glucose; D007328:Insulin; D005947:Glucose